Physics Work & Energy ETEA 2017
PMDC Verified Question 96 of 108
An engine pumps out 40 kg of water in one second. The water comes out vertically upwards with a velocity of \( 3 \text{ ms}^{-1} \), the power of engine in kilowatt is:
A
1.2 kW
B
12 kW
C
120 kW
D
1200 kW
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: 1.2 kW
Concept:

Power can be calculated using the force exerted and the velocity at which the mass moves. Since water is pumped vertically, the force must overcome gravity.

Formula:

$$ P = F \cdot v = (mg) \cdot v $$

Solution:

  • Mass per second (\( m/t \)) = 40 kg/s


  • Velocity (\( v \)) = \( 3 \text{ m/s} \)


  • Assume \( g = 10 \text{ m/s}^2 \) for standard ETEA simplicity.


  • \( P = (40 \times 10) \times 3 = 400 \times 3 = 1200 \text{ W} \)


  • Convert to kilowatts: \( 1200 \text{ W} = 1.2 \text{ kW} \)


Why other options are incorrect:

Forgetting to convert Watts to Kilowatts yields 1200 (Option D). Dividing by 10 instead of 1000 yields 120 kW. These are unit conversion errors.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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